DE 101 62 973 A1 discloses a drive control device in conjunction with an automatic transmission for an electrically drivable auxiliary oil pump. To this end, a mechanical main oil pump, which can be driven by the internal combustion engine, is used in combination with a motor stop automatic (MSA) element and the auxiliary oil pump. The auxiliary oil pump is necessary, for example, in the event of a traffic-related standstill of the motor vehicle since the motor stop automatic element will shut down the internal combustion engine and therefore the drive of the main oil pump. A sufficient oil-hydraulic volumetric flow rate and/or oil pressure must be made available for an automatic transmission so that, for example, the current gear remains engaged or the necessary actuators can be activated for a gear change that is performed while remaining stationary.
The drive of the electric auxiliary oil pump is unfavorable for the electrical on-board system of a motor vehicle and decreases its overall degree of effectiveness. In order to decrease these deficiencies, DE 101 62 973 A1 proposes to adjust the operating voltage, which is supplied to the electrically drivable auxiliary oil pump, based on the measured oil temperature of the automatic transmission. This is intended to maintain the necessary hydraulic pressure and prevent that hydraulic pressure is supplied that is greater than necessary.
In order to reduce the cost for an auxiliary oil pump, EP 1 223 365 A2 proposes a smaller embodiment of this auxiliary oil pump and, in certain operating conditions, to jointly operate the mechanical and the electrical oil pumps in order to maintain the necessary clutch pressure and, when the measured clutch pressure reaches a value, which the mechanically drivable main oil pump can supply by itself, to immediately shut down the auxiliary oil pump.
The state of the art is currently based on the volumetric flow rate and/or oil pressure, which is supplied by the mechanically driven main oil pump and/or the added electrical auxiliary oil pump, being sufficient for all occurring operating conditions.
In this context, the present invention is based on the object of creating a drive control device and a related method for an automatic transmission for a motor vehicle comprising a mechanically driven main oil pump and an electrically drivable auxiliary oil pump, which will make it possible to supply the necessary hydraulic volumetric flow rate and/or pressure in an extended operating range, for example also during the operation of a motor stop automatic element.